Improved plates for constructing burglar-proof safes



111131. The

size and afterward tempered or hardened. Al-

euezv he \VALTER K. MARVIN, OF NEIV YORK, N. Y.

': Specifieatronforming part of Letters Patent No. 11,529, datedFel.)rnary16,1864.

' I do hereby declare the following to be a full and clear descriptionthereof.

My invention relates to the manufacture of iron sheets or plates whichare impervious to drills employed under the conditions and provisionswhich are generally within the reach of and available to burglars, andthe construction of the outer walls or case of fire and burglar proofsafes with these prepared sheets or plates.

The means heretofore adopted for rendering the walls more diflieult todrill or cut consist First. In employing three or more sheetsot' metal,the first being wrought-iron and the others steel and iron, alternatelyarranged.

Secondly. In casting Ifranklinite iron onto the face of a sheetofWrought-iron and placing this east-iron faeii against another sheet ofwrong-Mt thin stratum of Franklinite intervenes the two shee rankliniteiron 1s so so etimes cast into sheets and simply placed between the twowrought-irom sheets, instead of castingit onto one of the sheets, asabove described. I may also mention that chilled castiron may beincluded in this class.

Thirdly. In the employment of various de vices consisting of peculiarmechanical and architectural arrangements of partsfor iiistance,'placingcast balls within the two sheets of iron, instead of a sheet ofcast-steel, franklinite, or chilled iron--the object of thesearrangements being that a drill penetrating the outer sheet and comingin contact with the balls will simply turn around with the ball and dono further harm, or, happening to strike between two balls or parts,would be wrenched and broken by the force employed to drive the drill.Other devices of this character have been suggested or used.

There are objections to each and all of these modes. The use of steel,as first named, involves great expense in the production of the walls,while it does not answer the purpose for which it is designed. Thesheet-steel thus employed is known to the trade as springsteel. It iscut up into pieces of the required though good spring-steel may bechosen for this purpose, yet it cannot be tempered so as to resist theaction of a drill made of the best refined steel, which, being small andeasily manageable, is tempered with great care and generally withsuperior skill. The second nodethat of employing franklinite-is muchless perfect than that of steel. This also true of chilled iron, as itis extremely brittle. Burglars have frequently overcome the apparentdiiticulty by cutting a disk from the outer sheet with a circular knife,and when the hard strata within are reached by fracturing the cast metalby a few blows of a hammer while the whole safe is muffled. The castmetal is thus made to crumble. The disk is then easily pried out, and nofurther obstacle is presented to the entrance of the safe. The lastmode, which relates to the use of balls and such like mechanicalarrai'igements, has proven in prac tice to be of little more utility inresisting the drill than would have been the case had the walls been ofsolid cast-iron,while sates made under such arrangements are generallyexpensive and bulky. Burglars have drilled through these walls withcomparative ease by drilling through the outer sheet of metal andcasting lead and sulphur through this aperture, so that the interiorpieces or balls were cemented together, and therefore no more offeredany obstruction to the further act-ion of the drill. In some cases theinterstices between the balls and other small pieces have been excellentreceptacles of the gunpowder employed by the burglars for blasting. Inother cases the burglars have simply cut a disk from the outer sheet ofiron and then removed the balls or other internal contrivance calculatedto deviate or break the tool, and they have then easily cut through theremaining sheets.

The object of my invention is to remedy difficulties, some of which Ihave designated, and I have accomplished it by the construction of wallsor plates for safes and other pur poses which cannot be drilled or cutby circular knives.

To carry out this my invention I first take one of the ordinary rollersemployed by iron workers for rolling out sheet-iron. This is put on aplaningmaching and corrugations or gutters of halt-circle form areplaned into its surface. The besteffect has been obtained by me byforming eduidistant grooves of about,

will issue from the rollers corrugated on oneside and plain-surfaced onthe other, in conformity with the surfaces of the two rollers betweenwhich it was passed. The next stepis to fill the gutters or depressionsin the corrugated side ;of the sheet with granulated or powdered c0-jrundum or emery. This having been done, a second sheet of any desirablethickness, but of smooth or plain surface, is placedover the emery, andthe two sheets are clamped or riveted together at the corners to preventtheir displacement. The whole is now removed to the reverberatoryfurnace and heated to a welding-heat. It is next taking out and passedthrough the ordinary rolling-mill, consisting of pairs of smoothrollers. The result is that one solid sheet is obtained, whichcontainsin its interior emery firmly embedded and held within aninfinite number of little matrices of iron, while externally there areno indications denoting other than an ordinary sheet of iron.

I have described a sheet constructed by corfrugating one of the twosheets of iron; but I have also, where heavy sheets have been desired,corrugated both sheets, and before placing the emery in the grooves Ihave riveted the two sheets together at the corners and cementedorsealed the ends of the tubes formed by bringing the two corrugatedsides of the sheets together with a cement made of potters clay andborax moistened a little with water.

Then placing the sheets on edge, with the sealed end down, I filledthc,grooves with emery, and

then closed the tubes on top with the cement. The wholeisthen putintothe reverberatory fu r- .3306 and heated to a welding-heat, and finally,passed through the rolling-mill.

I have been more particular in describing these modes because I haveobtained the best results from them; but I have obtained good I resultsby punching holes of one-eighth of an inch in diameter over the surfaceof one or both the sheets to about one-half of their thickness, and byfilling these with emery, and by otherwise proceeding as I havedescribed in the other two modes.

A great number ofpractical and comparative trials of sheets made in themanner I have described as of my invention with sheets made according tomodes heretofore practiced, some of which I have alludedto, haveestablished the superior resistance of the emery sheets to drills,circular knives, and other cutting-instruments. I have found that theeffect of the emery on the best prepared drill is that of chipping offthe edge in some instances and in others that of grinding away thecuttingedge of the drill. The peculiar hardness of the emery thusrenders the drill useless.

In describing my invention I have confined myself thus far to theconstruction of safes; but it is obvious that it has other applicationsequally important. It may be applied to the construction of prison-barsand to other purposes where it is desirable that the iron should beimpenetrable by saws, drills, and other cutting-instruments. It willlikewise be finderstood that the particular form of grooves, gutters, orholes or depressions is not essential to the carrying out of myinvention. I do not therefore desire to confine myseltLto the particularforms or modes which I have described as most convenient or readilypracticable in carrying out. my invention. Nor do I wish to beunderstood as limiting myself to the use of wrought-iron platesexclusively, as emery may be combined with steel or cast-iron; but whenapplied to the latter, owing to the brittleness of cast metals, theadvantages due to my invention could be easily counteracted.

Having thus described my invention and Q the manner in which the same isor may be car- I,

ried into efl'ect, I would state my claims fei lows: 1. As a newcomposition 0 mafier, iron or steel combined with em y, substantially inthe manner and for the purposes set forth.

2. Combin ng emery with malleable iron or steel by rolling process, asset forth. I 3. The manufacture of plates or sheets of iron or steel byweldingtogether two or more plates or sheets having emery interposed,sub-. stantially as herein set forth.

4. The method of making iron or steel plates having an emery core oremery confined in in cells throughout the interior, as described,

to this specification before two subscribing wit:

nesses.

WALTER K. MARVIN.

Witnesses J AMES M. RAYMOND, EDW'ARD BIssELL.

